Electric fuse.



C. W. DAVIS. ELECTRIC FUSE.

APPLICATION FILED MAY 19, 191s.

1,130,486, `Patented Mar. 2, 1915.

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Atty's .Q ffI Z f I UNITED CHARLES W. DAVIS, OF EDGEWORTH, -E1\TNS"YL`V.A`NIA, ASSEGNOR TO STANDARD UNDERGROUND CABLE COMPANY, OF PITTSBURGH, PENNSHVANA, A. CORPO- RATION OF PENNSYLVANIA.

ELECTRC FUSE.

Application filed May 19, 1913.

T0 @ZZ whomy it may concern:

Be it known that I, CHARLES W. DAVIS, residing 'at Edgeworth, in the county of Allegheny and State of Pennsylvania, a citizen ot' the United States, have invented or discovered certain new and useful improvements in Electric Fuses, of which improvements the following is a specication.

Hy invention relates to fuses or cut-outs adapted to break electric circuits when the current carried thereby becomes abnormal and dangerous, and has particularly to do with fuses for high potential currents.

In Yfuses for very high potential currents it is desirable, for various reasons, to reduce the length of the fusible element to such dimensions that an arc, upon the blowing of such element, is established between the free ends of the conductor. Various means have been employed to widen the gap between the free ends of the conductor adjoining the fusible element immediately after the fuse has blown, one of such means consisting in providing a casing to surround and inclose the fusible element and the conductors adjoining it, thus conlining the explosive forces generated upon the blowing of the fuse and rendering them effective to widen said gap. It has been found that, when the conductor within the casing is submerged in a bodyof arc-dampening liquid (which of course is relatively non-compressible) ,the explosive forces acting against such unyielding medium are liable to injure the casing or the box within which it is placed, or to so disturb the general structure as to cause serious inconvenience, it being understood of course that the explosive action of a fuse in a high potential circuit may be of very considerable magnitude.

It is the object of my present invention to provide a fuse of the character particularly described, but wherein the explosive forces of the fusible element will have no prejudicial effect upon the fuse structure.

In the accompanying drawing, which forms part of my specification, I have illustrated a single embodiment of my invention.

Figure 1 is a sectional view of a junction box showing two cables entering therein, the cores of such cables being connected by means of my limproved fuse structure, the casing of which is shown in longitudinal section; and Fig. 2 is a sectional view of the iuse casing taken on the line H-L Fig. 1.

Specication of Letters Patent.

Patented Mar, 2, Serial No. 768,597.

Having reference iirst to the general construction of the illustrative embodiment of my invention, the cables 1 extend through suitable openings in the bottom ot' the junction box i2, and are provided with terminal structures 3, there being a pair of spring clips 4 secured to the conductor of each cable. rhe fuse-inclosing casing 5 ot insulating material is secured to brackets 6 of conducting material, which in turn are attached to a frame or handle 7 provided with grooves 8 at its outer ends, such grooves being adapted to engage guide-posts 9', extending from the terminals 3. At the lower ends of the bracket 6 there are knife-blade contacts 10 adapted to be engaged by the spring clips 4.

The means which are particularly shown herein for rendering the' expansive forces generated upon the blowing of the fuse effective to widen the gap between the disrupted or fused conductor, consisto'f the tubular casing 5 having its outer ends closed by means of removable Stoppers or closures 11, the conductor within the casing comprising high fusion portions 12 and a central low fusion portion 13. The high fusion portions 12 extend through and are secured one to each closure 11, and electrical continuity is established between the outer ends of such high fusion portions and the brackets G by means of flexible conductors 14. As will readily be seen, the expansive forces, generated when the relatively short fusible element 13 blows, will be effective to quickly Idislodge the removable closures 11, which will carry with them the higher fusion conductor portions l2, thus widening the gap between their free ends. The arc-dampening liquid,such as oil or carbon tetra-chlorid, in this embodiment of my invention fills, not only the casing 5, but the junction box 2 to a level above such casing as is clearly indicated. In order to permit the liquid to circulate through the casing and thus cool the fusible element 13, the closures 11 may fit loosely in the openings of the easing 5, or small holes 15 may be provided through the walls of the casing.

In order to prevent the explosive forces of the fuse 'from exerting their effect immediately upon the relatively unyielding body of liquid in the casing, l provide a closed gascontaining chamber above the liquid and adjacent to the fusible element, such chamber tion between said casing parts.

Vhen the fusible element'13 blows, the gases generated thereby, seeking the path of least resistance, escape into and expand within the air chamber. Almost instantaneously the expanded gases exert their force against the body of liquid within the casing 5 and effect, without'explosive suddenness, a

widening of the gap between the free ends of the conductor portions 12.

I claim as my invention:

1. In an electric fuse, the combination of a fuse casing, a conductor therein comprising a low fusion portion and adjoining high fusion portions, means for rendering the expansive forces generated upon the blowing of said low fusion portion effective to widen the gap formed between the ends of'said high fusion portions, a body of arcdampening liquid in said casing, and a gascontaining chamber above and in communi-4 cation with the liquid within said casing, the gas within said chamber affording a compressible medium for the initial expan# sive forces upon the blowing of said low fusion portion of the conductor.

2'. In an electric fuse, the combination of a fuse casing, a conductor therein comprising a low fusioniportion and adjoining high fusionv portions, means for renderingv the expansive forces generated upon the blow.- ing of said low fusion portion effective to widen the gap formed between the ends of said high fusion portions, said conductor being submerged in a body of arc-dampening liquid, and a gas-containin chamber adjacent to said low-fusion portion and in communication with the interior of the fuse casing. f

3. In an electric fuse, the-combination of a tubular open-ended fuse casing, a conductor extending therethrough comprising a central low fusion portion 'and adjoining high fusion portions, removable closures for the ends of said casing each secured to one of said high fusion conductor portions and removable by the expansive forces generated `upon the blowing of said low fusible portion, a body of arc-dampening liquid within said casing, and a gas-containing chamber above the body of liquid withiny ing fluid within said junction box and with` in the casing surrounding the fuse, and a gas-containing chamber above and in communication with the liquid within said casing, the gas within said chamber affording a compressible medium .for the initial 'expansive forces generated by the blowing of vsaid low fusion conductor portion. -In an electric circuit opener, the combination of apair of electrically united conducting elements adapted when separated to break an electric circuit and movable with relation to each other when thus separated, an arc-dampening fluid surrounding the point of connection of s aid conductors, and a member forming a gas-containing chamber being in communication with the interior of the fuse casing and adjacent to said point of connection, the gas in said chamber affording a compressible medium for the initial expansive force effected by the arc formed upon the separation of said conductors.

In testimony whereof I have hereunto set my hand. CHARLES WV. DAVIS.

Witnesses:

J. LAWRENCE LYON,y FRNcIs J. ToMAssoN. 

